* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
body {
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
}
.guang {
  position: relative;
  display: inline-block;
  width: 220px;
  height: 80px;
  color: rgb(255, 255, 255);
  line-height: 80px;
  font-size: 35px;
  text-decoration: none;
  text-align: center;
  border-radius: 30px;
  background: linear-gradient(
    45deg,
    rgb(39, 122, 218),
    rgb(74, 230, 121),
    rgb(201, 214, 13),
    rgb(226, 20, 233),
    rgb(16, 172, 219)
  );
  background-size: 400%;
  z-index: 1;
  text-shadow: 0 0 5px white, 0 0 5px white;
}
.guang:hover {
  animation: move 1s linear alternate infinite;
}
@keyframes move {
  0% {
    background-position: 0%;
  }
  100% {
    background-position: 100%;
  }
}
.guang::before {
  content: "";
  position: absolute;
  top: -10px;
  left: -10px;
  width: 240px;
  height: 100px;
  background: linear-gradient(
    45deg,
    rgb(39, 122, 218),
    rgb(74, 230, 121),
    rgb(243, 169, 10),
    rgb(226, 20, 233),
    rgb(16, 172, 219)
  );
  background-size: 400%;
  opacity: 0;
  z-index: -1;
  border-radius: 45px;
  transition: 0.6s;
}
.guang:hover::before {
  filter: blur(15px);
  opacity: 1;
  animation: move 4s linear alternate infinite;
}
